KR20230021086A - Dual cure cyanate ester inkjet composition - Google Patents

Abstract

The present invention provides i) a photopolymerization-reactive compound (M) containing exactly one acryloyl group, ii) a photopolymerization-reactive compound (N) containing at least two acryloyl groups, iii) a radical photoinitiator (R), iv) (D) a cyanate ester compound containing at least two cyanate groups, and v) a cyanate ester curing catalyst (C), wherein (M) is different from (D) and (N) is (D) and 25 - 50 mol% of the contained acryloyl groups are provided by the reactive compound (N), and the mole ratio of the contained acryloyl groups to the contained cyanate groups of the compound (D) is from 0.30 to 0.95 phosphorus, 1.0 - 5.0 mol/kg acryloyl groups.

Description

Dual cure cyanate ester inkjet composition

The present invention relates to an inkjet composition, its use, a method for printing a three-dimensional object, and a three-dimensional object.

Three-dimensional (3D) printing or additive manufacturing is the process of manufacturing 3D digital models by the attachment of constituent materials. A 3D printed object is created by utilizing the object's CAD (computer-aided design) data through the sequential construction of two-dimensional (2D) layers corresponding to cross-sections of the 3D object. These layers were printed on top of each other, provided that each layer was quickly cured (eg by UV curing) before the next layer was printed accordingly.

One way to perform the 3D printing is inkjet printing: in inkjet printing, small droplets of ink (with limited viscosity) are projected directly onto the surface of the receiver without physical contact between the printing device and the ink-receiver. The printing device electronically stores printing data and controls a mechanism for imagewise ejection of droplets. Printing is accomplished by moving the print head across the ink-receiver or vice versa, or both.

3D inkjet printing is a relatively fast and flexible printing method for rapid manufacturing of complex 3D structures, tooling and creation of prototype parts directly from CAD files. Radiation curable compositions for use in three-dimensional printing methods of complex structures are described, for example, in WO 2004/096514. However, in general, there are many radiation curable compositions described in the art that can be used in the field of inkjet printing, such as in US 2017/173866, WO 2019/203134, WO 2020/065654 and WO 2020/211656.

Problems encountered in such 3D printing are poor mechanical properties such as low heat deflection temperature, brittleness, and aging meaning embrittlement over time and/or under temperature change and/or humidity. Another problem is the incomplete curing of the (initially) printed 3D object (so-called “green body”) and also various quality issues related to the final product (eg mechanical aspects and/or aging of the product). If the 3D object is fully cured during 3D printing, the adhesion between the layers may be too weak and the print may fail.

However, uncured resins inside the final product are also undesirable:

First, uncured liquid resin leakage (“bleeding”) from the printed 3D objects can cause health problems for end users, as liquid resins can contain reactive chemicals. Second, the printed 3D object does not reach optimal mechanical performance because uncured liquid resin can soften the object. Third, uncured resins can cause problems in some industrial applications of objects where high chemical inertia is required. In order to fully cure the printed "green body" object (to avoid the above disadvantages), a corresponding post-curing of the 3D "green body" is necessary.

Therefore, a suitable inkjet printing ink must simultaneously combine (satisfy) the following conditions: have a sufficiently low viscosity (to allow printing of small droplets through an inkjet nozzle), provide high viscosity stability (e.g. prior to printing must not polymerize in the printing device), sufficiently pre-curable (each printed ink layer must be pre-cured before the next layer is printed), and also efficiently post-curable (with the required quality characteristics). sufficiently curable in subsequent steps to give a 3D object).

Accordingly, an object of the present invention is to provide a high-quality injection printing ink that meets the requirements described above.

A solution for this purpose is

i) a photopolymerization-reactive compound (M) containing exactly one acryloyl group;

ii) a photopolymerization-reactive compound (N) containing at least two acryloyl groups;

iii) a radical photoinitiator (R);

iv) a cyanate ester compound (D) containing at least two cyanate groups and

v) cyanate ester curing catalyst (C)

Wherein (M) differs from (D) with the proviso that a cyanate ester compound containing exactly one acryloyl group and further containing at least two cyanate groups must be included in (D) do,

(N) differs from (D) with the proviso that a cyanate ester compound containing at least two acryloyl groups and further containing at least two cyanate groups must be included in (D),

25 - 50 mol% of the contained acryloyl groups are provided by the reactive compound (N), and the molar ratio of contained acryloyl groups to contained cyanate groups of compound (D) is from 0.30 to 0.95.

1.0 - 5.0 mol/kg of acryloyl groups.

The cyanate ester compound (D) (having the type R(-OCN) _x ) contains at least two cyanate groups (-OCN).

An acryloyl group according to the present invention is H ₂ C=CH-C(=O)- (which may be part of an “acrylic ester group” of the type H ₂ C=CH-C(=O)-O-). is defined as These groups are very reactive and efficient free radical polymerizers (also much more reactive, like methacrylic groups for example).

A photopolymerization-reactive compound (M) "containing exactly one acryloyl group" means containing neither more nor less than one acryloyl group.

(M) is different from (D)

It is meant that photopolymerization-reactive compounds (related species) containing exactly one acryloyl group and additionally containing at least two cyanate groups shall be included in (D) (and not included in (M)). However, the use of such “hybrid”-components is undesirable (and may be avoided).

Thus, (N) is different from (D)

A photopolymerization-reactive compound (related species) containing at least 2 acryloyl groups and further containing at least 2 cyanate groups shall be included in (D) (and not included in (N)). However, the use of such “hybrid”-components is undesirable (and may be avoided).

According to the present invention, the inkjet composition comprises (M) and (N) a photocurable compound (based on "light initiation") and (D) together with also a thermosetting compound.

Photocurable compounds can be polymerized and/or crosslinked in a first step by free radical (photo) polymerization, and thermocurable compounds are reacted (via polyaddition) in a subsequent thermal post-curing step.

The inkjet composition according to the present invention meets the following relevant quality requirements:

The composition provides the basis for sufficiently low viscosity to enable the production of small (ink ejectable) ink droplets. In addition, the composition provides the basis for sufficient viscosity stability, which is a basic requirement for maintaining a working printing process (eg gelation of the ink will block and even destroy the printer).

In addition, the inkjet composition according to the present invention enables the production of pre-products having sufficient mechanical properties, in particular pre-products having sufficient "green body strength": the green body strength after light-curing and heat-curing The stability of the object is explained before. Green body strength is a measure of the stability and crosslinking of a light-cured entity. However, it is undesirable to provide an excessively high green body strength: during post-processing (thermal curing) the UV-system ensures shape consistency, which keeps the thermal system in place before and during its curing/fixation means However, when the thermal system starts to harden, also depending on its nature, internal strains can be created that can destroy the UV-cured structure (especially if the crosslinking in the first photopolymerization step is too intensive) ( crack). The inherent and technically typical roughness of the relevant surfaces results in more facile crack formation due to the creation of internal strains. The use of the inkjet composition according to the present invention provides a kind of "compromise" that takes into account all of these different related issues - in particular: the crosslink must be sufficiently rigid to provide green body strength on the one hand and to hold the thermal cure system in place. But on the other hand, it must not be too brittle to withstand heat hardening.

A special "crosslinking strategy" justifying the advantages according to the present invention is reflected in the basic "laws" of inkjet compositions, which are decisively justified by the observance of the following (key) parameters I), II) and III):

I) an inkjet composition having 1.0 - 5.0 mol/kg acryloyl groups;

II) 25 - 50 mol % of the acryloyl groups contained are provided by the reactive compound (N);

III) The molar ratio of contained acryloyl groups to contained cyanate groups of compound (D) is from 0.3 to 0.95.

(Key) Parameter I):

If the value is too high, stronger tension is created in the green body - later crack formation is favored - if the value is too low, the green body strength is reduced: ultimately, above all, between the provision of strength, toughness and elasticity. A suitable compromise of .

(Key) Parameter II):

This parameter also provides a practical compromise solution between (green body) strength and elasticity. An excessively high concentration of polyacrylate also causes a significant increase in ink viscosity, thus making printability by inkjet more difficult. On the other hand, polyacrylates are particularly crucial for the formation of networks and, therefore, sufficient green body strength.

The mono-acrylates contribute to the toughness-compatibility balance of the matrix network of IPNs, especially in relation to tensile compensation during thermal post-curing, and also to the control of the hard and soft phases as well as the phase domains.

Observance of parameter II) ensures the correct balance of green body strength and flexibility: too low values lead to insufficient green strength, while too high values usually lead to problems with viscosity, but in particular unfavorable distortion (distortion: Provides macroscopic/optical characterization of curvature/bending of cast test specimens) resulting in:

The distortion ("as the bend of the "test specimen" - compared to the smooth surface") increases as the degree of crosslinking increases. In the injection process, these distortions can actually appear from layer to layer, favoring the formation of cracks between layers afterwards.

Curvature due to distortion can also be a problem since the next inkjet layer of an ink drop must always be applied to a smooth surface (height control, dynamic effects).

(Key) Parameter III):

In the broadest sense, this parameter ensures a balanced stabilization ratio by pre-hardening and post-hardening - taking into account, among other things, a compromise between green body strength and final body strength.

As the degree of hardening (pre-curing) of the first network increases, stronger stresses are created in the green body during the formation of the second thermal network (post-curing), which favor the formation of cracks (disadvantageously over-hardening). associated with higher values). However, sufficient green body strength is essential (too low values are ultimately disadvantageous in this respect).

Parameter III) as a relative ratio should always be viewed in combination with parameter I), which ultimately determines the networking density of both networks.

A further provided effect in connection with the use of the inkjet composition according to the present invention is that "bleeding" of the printed object prior to and during thermal curing is prevented (in particular during removal of the support structure into an aqueous liquid and thermal curing). While): Liquid material leaking from the printed 3D object may cause health problems to the end user, as the liquid resin may contain reactive chemicals.

According to a particular embodiment of the present invention, the inkjet composition may be provided as a kit: a corresponding kit-in-part inkjet composition is a combination of at least one photocurable compound and at least one thermosetting compound. And it may include a separate photoinitiator. The kit-in-part inkjet composition may include a combination of at least one photocurable compound, at least one thermosetting compound and a photoinitiator, and a separate curing catalyst. However, in most cases, the provision of such a kit is neither necessary nor advantageous (the kit can be avoided).

According to a preferred embodiment, the inkjet composition according to the invention has 1.7 - 3.5 mol/kg acryloyl groups. Typically, 30 - 45 mol% of the acryloyl groups contained in the inkjet composition are provided by the reactive compound (N). With regard to the provision of a pre-product (and also an end product) which is not too brittle (cracking prone) on the one hand, but also not too soft on the other hand, the above two features "contained mol/kg acryloyl groups" and The appropriate (quantitative) combination of "mol % of contained acryloyl groups provided by reactive compound (N)" is also important.

According to a preferred embodiment, 80 - 100 mol %, preferably 90 - 100 mol %, of the reactive compound (N) in the inkjet composition is provided by a species containing 3 or fewer acryloyl groups. However, it is important to consider this regularity in combination with the other features "mol/kg acryloyl groups contained" and "mol % of acryloyl groups contained provided by the reactive compound (N)" above, as these This is because the (correct quantitative) combination of characteristics has been identified as a fundamental requirement for the provision of working processes on the one hand and the production of high-quality products on the other hand.

Monoacrylates (particularly compound (M)) often contribute with respect to moderate viscosities of inkjet compositions (particularly medium molecular weight species). Higher amounts of mono acrylate reduce the degree of crosslinking.

The following mono acrylates may be used:

Ethyl acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, 2-phenoxyethyl acrylate, isodecyl acrylate, isooctyl acrylate, tridecyl acrylate, caprolactone acrylate, ethoxy sylated nonyl phenol acrylate, isobornyl acrylate, hexadecyl acrylate, monomethoxy tripropylene glycol monoacrylate, monomethoxy neopentyl glycol propoxylate monoacrylate, B-carboxyethyl acrylate, and/or Oxyethylated phenol acrylate.

According to a preferred embodiment, the mono acrylate is dihydrodipentadienyl acrylate (CAS: 12542-30-2), cyclic trimethylolpropane formal acrylate (CAS: 66492-51-1), tricyclodecane Methanol Acrylate (CAS: 93962-84-6), 2-Phenylethyl Acrylate (CAS: 3530-36-7), 2-Hydroxy-3-phenoxypropylacrylate (CAS: 16969-10-1) , 2-[(butylcarbamoyl)oxy]ethyl acrylate (63225-53-6) and/or 4-hydroxybutyl acrylate (2478-10-6).

However, the most preferred mono acrylate species are isobornyl acrylate, acryloyl morpholine, 2-[(butylcarbamoyl)oxy]ethyl acrylate or mixtures thereof.

The following diacrylates may be used: 1,3 butylene glycol diacrylate, 1,4 butanediol diacrylate, diethylene glycol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate, Polyethylene glycol diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, ethoxylated bisphenol A diacrylate, propoxy Sylated neopentyl glycol diacrylate, ethoxylated neopentyl glycol diacrylate, ethoxylated tripropylene glycol diacrylate and/or monomethoxy trimethylolpropane ethoxylate diacrylate.

The following triacrylates may be used: trimethylol propane triacrylate, tris (2-hydroxy ethyl) isocyanurate triacrylate, ethoxylated trimethylol propane triacrylate, propoxylated glycerol triacrylate ditrimethyl all propane triacrylate, pentaerythritol triacrylate, and/or propoxylated trimethylolpropane triacrylate.

However, preferred polyacrylates (especially as photopolymerization-reactive compounds (N) containing at least two acryloyl groups) are trimethylolpropane lyacrylate, tricyclodecane dimethanol diacrylate (CAS: 42594-17-2) , polyethylene glycol diacrylate (CAS: 25322-68-3), polypropylene glycol diacrylate (CAS: 52496-08-9), poly(propylene glycol) dimethacrylate (CAS: 25852-47-5) , Dipropylene Glycol Diacrylate (CAS: 57472-68-1), Trimethylolpropane Trimethacrylate (3290-92-4), Bisphenol A Glycerolate Diacrylate (CAS: 4687-94-9), Tris Isocyanurate triacrylate (CAS: 40220-08-4), bisphenol A epoxy diacrylate (CAS: 55818-57-0) and/or trimethylolpropane tetraacrylate (CAS: 94108-97-1) am.

The photocurable compound(s) are included in the inkjet composition in molar amounts as specified above - this may be, for example, in an amount of 20 to 50 wt%, based on the total weight of the inkjet composition.

The photopolymerization reactive compound (species of (M) and (N)) and the radical photoinitiator (R) may be included in the inkjet composition in a weight ratio of 95:5 to 99.5:0.5, preferably 97:3 to 99:1.

Photoinitiators (R) generate reactive species (free radicals) upon exposure to radiation (eg UV or visible light).

The photoinitiator may be included in the inkjet composition in an amount of 0.2 to 4 wt % based on the total weight of the inkjet composition.

According to one embodiment, the species of radical photoinitiator (R) is a phosphine oxide based photoinitiator, preferably diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and/or phenyl bis(2, 4,6-trimethylbenzoyl)phosphine oxide.

The contained thermosetting compound is a compound capable of addition polymerization (polyaddition) and/or crosslinking upon exposure to heat. Preferably, the heat curable compound should polymerize and/or crosslink at temperatures below 100°C. According to the present invention, a cyanate ester compound (D) containing at least two cyanate groups is provided as a thermosetting compound.

In the injection composition with respect to the achieved qualities (especially mechanical properties), on the one hand, with respect to light-reactive groups (pre-hardening according to the first step) and on the other hand with respect to thermally reactive groups (post-hardening activity) It is important that there is an appropriate proportion of In this regard, it is preferable that the molar ratio of contained acryloyl groups to contained cyanate groups of compound (D) in the inkjet composition is 0.36 to 0.94.

Cyanate ester compounds (D) containing at least two cyanate groups are well known by those skilled in the art. Related species are known as polycyanate esters, which are preferably aromatic or aliphatic diisocyanate esters, especially aromatic diisocyanate esters.

Related species may include bisphenol E-based cyanate esters (AroCy® L-10), novolac-based cyanate esters (AroCy® XU 371), bisphenol M-based cyanate esters (AroCy® XU 366 and AroCy® XU 378). can The cyanate ester may preferably be a cyanate ester based on bisphenol E (AroCy® L-10) or a cyanate ester based on novolac (AroCy® XU 371).

The cyanate ester compound (D) containing at least two cyanate groups is in an amount as defined above (indirectly Defined by: by the molar ratio of contained acryloyl groups to contained cyanate groups of compound (D)) in the inkjet composition.

According to a particular embodiment, at least 30 wt % of the species of (D), preferably at least 60 wt % of the species of (D) are provided by 4,4′-ethylidenediphenyl dicyanate (e.g. eg provided by "AroCy® L-10").

The curing catalyst used must be chosen judiciously to initiate the thermal reaction at a specific temperature much higher than the temperature during printing. This temperature should not be too high as the UV-system may not be able to withstand temperatures above 220°C for long periods of time. At the same time, they should be as low as possible reactive under printing conditions. They must operate in such a way that they can drive the thermal reaction to the highest conversion rate. They should not destabilize the UV-system and they should withstand possible washing procedures to remove the support structure used (as described below). If the relevant manufacturing procedures are to work well and good product quality is to be achieved, it may be advantageous if the species of cyanate ester curing catalyst (C) is provided by an aluminum metal catalyst, preferably by aluminum acetylacetonate.

However, the cyanate ester curing catalyst (C) may generally be a chelated metal catalyst, preferably based on a chelated aluminum catalyst.

The metal catalyst may be included in the inkjet composition in an amount of 100 to 3000 ppm, preferably 300 to 2000 ppm, based on the total weight of the cyanate ester compound (D) containing at least two cyanate groups in the inkjet composition. there is.

According to a preferred embodiment, 90 - 100 wt%, preferably 97 - 100 wt% of the components contained (in the inkjet composition) are (M), (N), (R), (D) and (C) provided by the species.

The addition of other components is possible, but this is not advantageous in many cases (e.g. if there is no contribution with respect to the curing effect or if undesirable thermal reactivity below 100° C. is caused): The use of inert solvents (which cannot be photopolymerized in the first step or post-cured in the second step) is not preferred. Preferably, the inkjet composition contains less than 8 wt% of an inert solvent, more preferably less than 2 wt%. Also, the use of radically polymerizable monomers that do not contain (higher amounts) acryloyl groups (such as methacrylates) are not preferred. Preferably, the inkjet composition contains less than 6 wt%, more preferably less than 2 wt% of radically polymerizable monomers that do not contain acryloyl groups. For example, methacrylates are not sufficiently reactive, eg with respect to (short) radical photopolymerization. Preferably, the inkjet composition contains less than 6 wt%, more preferably less than 2 wt% meth acrylate (containing no acryloyl groups).

To avoid undesirable side reactions (which typically increase viscosity), it is preferred that the inkjet composition does not contain cationic or anionic (photo)polymerization initiators. In any case, it is desirable to avoid compounds (particularly those in high amounts) that react at temperatures below 100° C. in the composition via one of the step reaction types: polyaddition, polycondensation. These compounds (especially in higher amounts) can cause problems with the desired viscosity stability. To enable jetting of the inkjet composition through a thin nozzle it is essential to limit its viscosity.

Typically, the inkjet composition has a viscosity at 45° C. of 10 - 40 mPa s, where the viscosity is determined by a thermally controlled rotational rheometer (Anton Paar Physica) of cone-plate geometry. MCR 300, cone diameter: 60 mm, zero-gap distance: 0.061 mm, cone angle: 0.5°, shear-rate 600 s-1).

However, the inkjet composition according to the present invention may further contain a stabilizer, a wetting agent, an antifoaming agent, a radical polymerization inhibitor and/or a pigment. Usually, dissolved oxygen acts as a radical polymerization inhibitor, but additional synthesis inhibitors may be used.

The present invention also relates to a method for printing a three-dimensional object comprising the following steps:

(a) jetting the inkjet composition as described above by a printing machine to form a layer into a configured pattern corresponding to the shape of the object;

(b) irradiating the formed layer with light to form a light-cured layer;

(c) sequentially repeating steps (a) and (b) to form a plurality of light-cured layers to manufacture a green body of a three-dimensional object; and

(d) post-curing the three-dimensional object by heating the green body.

Typically, additional support ink is printed and cured to stabilize the green body, wherein the cured support ink is water soluble and is removed by treatment with an aqueous wash solution after step c) and before performing step (d).

Typically, step (d) is carried out in such a way that a temperature of 110 to 140° C. is maintained for at least 5 hours.

Typically, the associated temperature increase in heating step (d) is limited to 2 K/min.

Preferably, light irradiation in step (b) is performed by a UV lamp, and the exposure time of each ink layer is 0.1 - 2 s.

A typical procedure may be as follows:

The inkjet composition can be filtered before using it as an inkjet composition. Preferably, the inkjet composition is filtered in such a way that it does not contain particles having a particle size greater than 1 μm. Ink is then loaded into the printer. To better ensure homogeneity and constant temperature, the system is recirculated for at least 2 hours. During printing, a support ink (e.g., acrylamide based) is ink-jetted and UV-cured to create a mold for the object ink that is subsequently ink-jetted and UV-cured (wet on dry printing ). To control the layer thickness, all inks are leveled once in their liquid state on the building tray, which takes place after ink-jetting and before UV-curing during the dynamic wetting process on the substrate. In this way a 3D-object is created. The support ink is printed layer by layer (with the layer of the green body) such that after the printing process the object (green body) is surrounded by a support material (eg polyacrylamide). To remove the support material, the entire structure is placed in a water bath and heated to 35-40° C. in the presence of ultrasound. Depending on the support material and the geometry of the object, the cleaning process takes 0.5 h - 24 h, sometimes even longer. Once all support structures are removed, the objects are removed from the water bath and allowed to air dry at room temperature. After drying for about 5 h, the object is placed in a heating chamber (a type of oven) where, depending on the chemistry, geometry and application, the thermal curing system present in the printed and now cleaned object is well suited to heat-cure it. selected temperature program. It is advantageous to initiate the thermal reaction slowly to avoid strong exothermic heat generation and to give the UV-cured system time to relax. After appropriate heat curing, slow cooling is advantageous to prevent the capture of internal stresses.

The invention also relates to a three-dimensional object produced according to the method as described above.

The three-dimensional object has a tensile strength of 21-40 MPa, preferably 41-100 MPa and an elongation at break of 2.1 - 5%, preferably greater than 5%, and an E- may have a modulus.

Further, the present invention relates to the use of an inkjet composition as described above for the production of three-dimensional objects.

Common measurement method

Viscosity was measured according to DIN EN ISO 3219 at a temperature of 40 °C to 60 °C with a heating ramp of 2 K/min using a thermally controlled rotational rheometer (Anton Par Physica MCR 300, cone diameter: 60 mm, cone-plate geometry). Zero-gap distance: 0.061 mm, cone angle: 0.5°, shear-rate 600 s ^-1 ). For comparison, viscosities at 50° C. or 60° C. are shown in the examples below. The storage stability of the ink was determined in the same experiment as described above after storage at 60° C. for 2, 5, 7 and/or 8 days in closed sample bottles.

Shore hardnesses A and D are DIN by an OS-2 measuring device from Hildebrand Pruef- und Messtechnik GmbH with cylindrical specimens with a diameter of 40 mm and a thickness of 7 mm. It was measured according to EN ISO norm 7619. The needle was placed on the specimen and the result was obtained on the balance after 3 seconds. Measurements were repeated 5 times.

Green body strength is measured by creating rectangular specimens with dimensions of 40 mm x 7 mm x 2 or 4 mm (b x a x c) of each formulation by UV-irradiation. This specimen was placed on two PTFE-blocks with a volume of 100 mm x 5 mm x 5 mm. The span width was 35 or 75 mm. The set-up was kept at room temperature and inspected for bending/deformation after 1.5 h. To quantify the different formulations, a grading system was defined: A) no bending was directly observed from the initial rectangular specimen (i.e., 0% bending) or a range of 5% or less, 3% or less, 1% or less. This means that it is rarely observed. The percentage in bend is defined as comparing the center position of a rectangular specimen at the start of setup at time 0 (e.g. dimensions 20 mm x 3.5 mm x 2 mm (b x a x c)) and at the end of setup at time 1.5 h. . B) means that the bending becomes more pronounced and the specimen exhibits a bending greater than 5% to 20%. C) means that the specimen exhibits a bending greater than 20% to nearly contact with the ground. D) indicates that the specimen touches the ground. The same was done after curing in the oven-curing program mentioned above. Tensile tests were performed on a Zwick-Roell tensile tester 1445 according to DIN EN ISO norm 527-1 with 5A specimens. The E-modulus was determined from the slope of the stress-strain curve at strains of 0.05–0.25% at 1 mm/min. Tensile strength and elongation at break were determined by pulling the specimen at 5 mm/min against a rigid material.

A three-point bending test for the measurement of flexural strength and modulus was performed on a Zwick-Röh 1445 according to DIN EN ISO norm 178 with a bending transducer of 500 N and a specimen with dimensions of 80 x 10 x 4 mm. The test specimen was subjected to a span distance of 64 mm with a compression pin with a radius of 5 mm at a crosshead speed for flexural modulus of 2 mm/min (0.05-0.25% elongation range) and a subsequent test speed of 10 mm/min until failure. bent from the center in

Impact strength was measured using an IZOD setup according to DIN EN ISO norm 180 with an unnotched specimen with dimensions of 80 x 10 x 4 mm and an impact weight of 2.75 J on a Zwick HIT5.5P Plus.

Heat deflection temperature B (0.45 MPa) or A (1.80 MPa) as a three-point-bending test HDT-determination from Coesfeld on specimens with dimensions of 80 x 10 x 4 mm according to DIN EN ISO 75 It was performed on an instrument Compact 3. The heating rate was set at 2 K/min in the range from 30° C. to reaching the HDT-value.

The glass transition temperature as well as the network density were measured in a thermomechanical analysis (TMA) 3-point-bending set-up (TMA/SDTA2+) from Mettler Toledo with specimen dimensions of 10 x 5 x 1.2 mm with reference to DIN EN ISO 11359. LN2) was determined using. The heating rate was 5 K/min in the range of 20-300 °C, and the alternating load in sinusoidal mode was set at 0.02 to 1.0 N. The network density was then calculated by dividing the 50 K storage modulus above T _g by 3 as an empirical factor, the gas constant R, and the temperature 50 K above T _g in Kelvin.

The warpage of the 5A-specimens from tensile tests after UV- and thermal curing in the oven-curing program mentioned above was determined by examining the bend/strain in such a way that the grading system is defined as follows: A) is from the initial specimen. It means that no bending was observed (i.e., 0% bending) or little was observed in the range of 5% or less, 3% or less, 1% or less. The percentage in bend is defined by comparing the position of the center of the specimen in the sole plate to the outer jaw that can be lifted from the sole plate. B) means that the bending becomes more pronounced and the specimen exhibits a bending greater than 5% to 10%. C) means that the specimen exhibits a bending of 10-20%. D) indicates that the bending of the specimen is greater than 20%.

The present invention is further described below using examples.

General terms and definitions

Reagents Used in Examples

- Isobornylacrylate (IBOA) - CAS No 5888-33-5 from SARTOMER

- Acryloylmorpholine (ACMO) - CAS No 5117-12-4 from RAHN

- Trimethylolpropane triacrylate (TMPTA) - CAS No 15625-89-5 from Sartomer

- CN981 - Polyether Ester Urethane Diacrylate - CAS No 72162-39-1 from Sartomer

- BHT - CAS No 128-37-0 from SIGMA ALDRICH

- Omnirad 819 - Photoinitiator with CAS No 162881-26-7 from IGM Resins

- Genorad 16 - polymerization inhibitor which is a combination of glycerol propoxylate (1PO/OH) and 4-methoxyphenol from Ran

- AroCy 10 L US - Bisphenol-E based cyanate ester - CAS No 47073-92-7 from HUNTSMAN

- Al(acac) ₃ - CAS No 13963-57-0 from Sigma Aldrich

- Co(acac) ₃ - CAS No 21679-46-9 from Sigma Aldrich

- BYK 333 - polyether modified polydimethylsiloxane additive from BYK

Example 1:

Isobornylacrylate (IBOA) (25.0 wt%), Acryloyl Morpholine (ACMO) (12.5 wt%), Trimethylpropane Triacrylate (TMPTA) (12.5 wt%), Butylhydroxytoluol (BHT) (0.3 wt%), Omnirad 819 (1.0 wt%), Genorad 16 (0.5 wt%), BYK 333 (0.2 wt%), AroCy 10 L US (48.2 wt%) (bisphenol with two cyanate groups- E-based cyanate ester) and an additional 500 ppm Al(acac) ₃ were mixed and filtered over 1 μm.

The ink was inkjet UV printed and post-cured from RT to 220° C. with a heating ramp of 1 K/min.

The final properties of the final object were as follows:

Tensile Strength: 75 MPa

Elongation at Break: 2.5%

E-modulus: 3200 MPa

Measure green body after UV-curing (40 x 7 x 4 mm) A

Green body measurements after heat-curing (40 x 7 x 4 mm): A

The inkjet composition includes:

I) mol/kg acryloyl groups of (M) and (N): 3.35

II) mol % of acryloyl groups provided by the reactive compound (N): 37.8

III) Molar ratio of contained acryloyl groups (M) and (N) to contained cyanate ester groups of compound (D): 0.92

Example 2:

Isobornylacrylate (12.5 wt%), Acryloyl Morpholine (7.5%), Trimethylolpropane Triacrylate (7.5%), BHT (0.3 wt%), Omnirad 819 (1 wt%), Genorad 16 (0.5 wt%), BYK 333 (0.2 wt%), AroCy 10 L US (68.2 wt%) as a bisphenol-E based cyanate ester and an additional 1500 ppm Al(acac) ₃ were mixed and filtered over 1 μm. .

The ink was inkjet UV printed and post-cured from RT to 220° C. with a heating ramp of 1 K/min.

The final properties of the final object were as follows:

Tensile strength: 80 MPa

Elongation at Break: 2.7%

E-modulus: 2900 MPa

HDT B: 196°C

Green body measurements after UV-curing (40 x 7 x 4 mm) B

Green body measurements after heat-curing (40 x 7 x 4 mm): B

The viscosity stability of Example 2 is measured as follows:

The inkjet composition includes:

I) mol/kg acryloyl groups of (M) and (N): 1.89

II) mol% of acryloyl groups provided by the reactive compound (N): 40.2

III) Molar ratio of contained acryloyl groups (M) and (N) to contained cyanate ester groups of compound (D): 0.37

Example 3

For AroCy 10 L US as the thermally reactive component, the viscosity was measured after storage at 60° C. in the presence of different catalysts and concentrations and at different time intervals (see table below).

The increase in viscosity in the presence of cobalt-catalyst is more pronounced than for aluminum catalyst.

Example 4

Isobornylacrylate (20.8 wt%), Acryloyl Morpholine (10.3 wt%), Trimethylolpropane Triacrylate (10.3 wt%), CN 981 (6.32 wt%), Omnirad 819 (1.0 wt%) , Genorad 16 (0.25 wt%), BYK 333 (0.2 wt%) AroCy 10 L US (51.0 wt%) and aluminum acetylacetonate (0.03 wt%) were mixed and filtered over 1 μm.

The ink was inkjet UV printed and post-cured as follows: 30-130° C. at 1 K/min, 130° C./10 h, 130-150° C. at 1 K/min, 150° C./2 h, 150° C. at 1 K/min -180℃, 180℃/2h, 180-200℃ at 1 K/min, 200℃/2h, 200-220℃ at 1 K/min, 220℃/10min, 220-30℃ at -5 K/min.

The final properties of the final object were as follows:

Tensile strength: 86 MPa;

Elongation at break: 3.9%;

E-modulus: 3500 MPa.

HDT B: 141°C

Measure green body after UV-curing (40 x 7 x 4 mm) A

Green body measurements after heat-curing (40 x 7 x 4 mm): A

The inkjet composition includes:

I) mol/kg acryloyl groups of (M) and (N): 2.85

II) mol% of acryloyl groups provided by the reactive compound (N): 39.3

III) Molar ratio of contained acryloyl groups (M) and (N) to contained cyanate ester groups of compound (D): 0.74

Example 5

Isobornylacrylate (17.1 wt%), Acryloyl Morpholine (7.8 wt%), Trimethylolpropane Triacrylate (7.3 wt%), CN 981 (6.3 wt%), Omnirad 819 (0.5 wt%) , Genorad 16 (0.25 wt%), BYK 333 (0.2 wt%) AroCy 10 L US (60.0 wt%) and aluminum acetylacetonate (0.03 wt%) were mixed and filtered over 1 μm.

The ink was inkjet UV printed and post-cured as follows: 30-130° C. at 1 K/min, 130° C./10 h, 130-150° C. at 1 K/min, 150° C./2 h, 150° C. at 1 K/min -180℃, 180℃/2h, 180-200℃ at 1 K/min, 200℃/2h, 200-220℃ at 1 K/min, 220℃/10min, 220-30℃ at -5 K/min.

The final properties of the final object were as follows:

Tensile strength: 86 MPa;

Elongation at break: 4.2%;

E-modulus: 3400 MPa.

HDT B: 194°C

Measure green body after UV-curing (40 x 7 x 4 mm) A

Green body measurements after heat-curing (40 x 7 x 4 mm): A

The inkjet composition includes:

I) mol/kg acryloyl groups of (M) and (N): 2.19

II) mol % of acryloyl groups provided by the reactive compound (N): 37.2

III) Molar ratio of contained acryloyl groups (M) and (N) to contained cyanate ester groups of compound (D): 0.48

Example 6

Isobornylacrylate (20.7 wt%), Trimethylolpropane Triacrylate (6.7 wt%), CN 981 (4.4 wt%), Omnirad 819 (2.3 wt%), Genorad 16 (0.29 wt%), BYK 333 (0.2 wt%) AroCy 10 L US (65.4 wt%) and aluminum acetylacetonate (0.033 wt%) were mixed and filtered over 1 μm.

The ink was inkjet UV printed and post-cured as follows: 30-130° C. at 1 K/min, 130° C./10 h, 130-150° C. at 1 K/min, 150° C./2 h, 150° C. at 1 K/min -180℃, 180℃/2h, 180-200℃ at 1 K/min, 200℃/2h, 200-220℃ at 1 K/min, 220℃/10min, 220-30℃ at -5 K/min.

The final properties of the final object were as follows:

Tensile strength: 86 MPa

Elongation at Break: 3.5%

E-modulus: 3400 MPa

HDT B: 189°C

HDT A: 124°C

Flexural strength: 111 MPa

Flexural modulus: 2800 MPa

Unnotched Izod: 264 J/m

The inkjet composition includes:

I) mol/kg acryloyl groups of (M) and (N): 1.72

II) mol% of acryloyl groups provided by the reactive compound (N): 42.5

III) Molar ratio of contained acryloyl groups (M) and (N) to contained cyanate ester groups of compound (D): 0.35

Examples 7-11

To screen ink and material properties of possible inkjet formulations, molded specimens were irradiated with UV-light (LED 395 nm, 16 W/cm ² ) from each side of a translucent silicone mold from the bottom at a distance of 15 cm for 30 s. harden Thermal post-curing is then carried out. The test results of these light-cured and oven-cured bulk specimens in turn highlight the good proximity of the final material performance of the material sprayed and post-cured formulations, although the preparation process for the first curing-stage of the interpenetrating system is different. .

Examples 7-11 demonstrate various formulation ratios in such a way that the degree of functional acrylate groups by (N) is within or beyond the limits of claimed dual-cure inkjet inks to highlight the correlation of printing applications and material characteristics. exemplify

Isobornyl acrylate, acryloyl morpholine, trimethylpropane triacrylate, Omnirad 819, Genorad 16, AroCy 10 L US and Al(acac) ₃ were mixed in the ratios shown in Table 1.

The ink was molded as described above and post-cured as follows: 30-130° C. at 1 K/min, 130° C./10 h, 130-150° C. at 1 K/min, 150° C./2 h, 1 K 150-180℃ at /min, 180℃/2h, 180-200℃ at 1 K/min, 200℃/2h, 200-220℃ at 1 K/min, 220℃/10min at -5 K/min, 220 -30℃.

As shown in Table 1, the ink and material properties depend on the increase in network density due to the increase in mol% by (N). Thus, the strength of the green body labeled C is too low and the material in the green state is too soft, whereas the warpage of category D is too high and the material can print complex three-dimensional objects with sufficient dimensional accuracy with respect to digital files and post- It has too much internal tension to cure. In addition, excellent final mechanical properties in terms of toughness and flexibility, preferably of 70-100 MPa tensile strength, also preferably of 3-5% elongation at break, only balance the degree of functional acrylate groups by (N) is achieved by doing

Table 1

Table 1:

Claims (20)

As an inkjet composition having 1.0 - 5.0 mol/kg acryloyl groups,
i) a photopolymerization-reactive compound (M) containing exactly one acryloyl group;
ii) a photopolymerization-reactive compound (N) containing at least two acryloyl groups;
iii) a radical photoinitiator (R);
iv) a cyanate ester compound (D) containing at least two cyanate groups, and
v) cyanate ester curing catalyst (C)
including, where
(M) differs from (D) with the proviso that a cyanate ester compound containing exactly one acryloyl group and further containing at least two cyanate groups must be included in (D),
(N) differs from (D) with the proviso that a cyanate ester compound containing at least two acryloyl groups and further containing at least two cyanate groups must be included in (D),
25 - 50 mol% of the contained acryloyl groups are provided by the reactive compound (N), and the molar ratio of contained acryloyl groups to contained cyanate groups of compound (D) is from 0.30 to 0.95.
Inkjet composition. The inkjet composition according to claim 1, having 1.7 - 3.5 mol/kg acryloyl groups. 3. The inkjet composition according to claim 1 or 2, wherein 30 - 45 mol% of the acryloyl groups contained are provided by the reactive compound (N). 4. The method according to any one of claims 1 to 3, wherein 80 - 100 mol%, preferably 90 - 100 mol%, of the reactive compound (N) is provided by species containing up to 3 acryloyl groups. phosphorus inkjet composition. The inkjet composition according to any one of claims 1 to 4, wherein the molar ratio of contained acryloyl groups to contained cyanate groups of compound (D) is from 0.36 to 0.94. 6. The method according to any one of claims 1 to 5, wherein at least 30 wt% of the species of (D), preferably at least 60 wt% of the species of (D), is 4,4'-ethylidenediphenyl dicy An inkjet composition provided by Anate. 7. The method according to any one of claims 1 to 6, wherein the type of radical photoinitiator (R) is selected from a phosphine oxide based photoinitiator, preferably diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and/or or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. 8. The inkjet composition according to any one of claims 1 to 7, wherein the species of cyanate ester curing catalyst (C) is provided by an aluminum metal catalyst, preferably aluminum acetylacetonate. 9. The method according to any one of claims 1 to 8, wherein 90 - 100 wt%, preferably 97 - 100 wt% of the components contained are (M), (N), (R), (D) and ( The inkjet composition provided by the species of C). 10. The method according to any one of claims 1 to 9, having a viscosity of 10 - 40 mPa s at 45 ° C, wherein the viscosity is 40 ° C to 60 ° C with a heating ramp of 2 K / min according to DIN EN ISO 3219 Thermally controlled rotational rheometer of cone-plate geometry, cone diameter: 60 mm, zero-gap distance: 0.061 mm, cone angle: 0.5°, shear-rate 600 s-1 measured at a temperature of up to composition. The inkjet composition according to any one of claims 1 to 10, which does not contain a cationic or anionic (photo)polymerization initiator. 12. The inkjet composition according to any one of claims 1 to 11, which contains less than 6 wt%, more preferably less than 2 wt%, of radically polymerizable monomers that do not contain acryloyl groups. The inkjet composition according to any one of claims 1 to 12, further comprising a stabilizer, a wetting agent, an antifoaming agent, a radical polymerization inhibitor and/or a pigment. As a printing method of a three-dimensional object,
(a) spraying the inkjet composition according to any one of claims 1 to 13 by a printing machine to form a layer with a configured pattern corresponding to the shape of the object;
(b) irradiating the formed layer with light to form a light-cured layer;
(c) sequentially repeating steps (a) and (b) to form a plurality of light-cured layers to produce a green body of the three-dimensional object; and
(d) post-curing the three-dimensional object by heating the green body
How to include. 15. The method of claim 14, further printing and curing a support ink to stabilize the green body, wherein the cured support ink is water soluble and is removed by treatment with an aqueous wash solution after step c) and before performing step (d). how it would be. 16. The method according to claim 14 or 15, wherein step (d) is carried out in such a way that a temperature of 110 to 140° C. is maintained for at least 5 hours. 17. The method of claim 16, wherein the associated temperature increase in heating step (d) is limited to 2 K/min. 18. The method according to any one of claims 14 to 17, wherein the light irradiation in step (b) is performed by a UV lamp, and the exposure time of each ink layer is 0.1 - 2 s. A three-dimensional object manufactured according to the method according to any one of claims 14 to 18. Use of the inkjet composition according to any one of claims 1 to 13 for the production of three-dimensional objects.